johnknowsnothing
Cadet
- Joined
- Jul 7, 2011
- Messages
- 11
1975, Johnson 25HP, Tiller Short staff Engine shuts off while going full speed ah
1975, Johnson 25HP, Tiller Short staff Engine shuts off while going full speed ah
Here's the answer. Opened up the lower unit. Replaced the water pump wheel. The original had bent spokes. Probably not spinning correctly and shooting the water up to the engine and overheated the engine, which caused it to die. Because it over heated, Totally blew the rubber head gasket. Lost total compression in the pistons.
Also sanded down the gasket cover fitting to make sure it was smooth again. Luckily, the carbs and cylinders weren't destroyed or baked. Put that back together. Pulled the plugs. Checked the compression. Close to 110. Not great but not too bad. Changed the spark plugs. Removed the temperature cover and the thermostat was fried. Took thermostat out all together and left it out (some people say you need it, some say you don't). Ran the motor and water was spewing up out so the lower unit water pump wheel was most likely the culprit. I put thermostat cover back on. I also changed the condensers, and the wires to the 2 blue spark boxes. Forgot the name of those. Put in a new rubber gasket in the fuel adjuster lever too (tiny rubber band looking thing). Ran some carb cleaner in the carb while running (in water tank). Smoked like hell. Checked lower unit lube and that is fine. Running Yamalube Gear Grease in the Lower unit. Running 50:1 Yamalube M-2 in the gas tank. The motor is running fine, spitting water out fine. Got it onto the lake and it runs like a beast. No problems as of yet. Runs smooth and because I adjusted and fixed the small rubber gasket in the fuel adjuster, idle is nice and slow when not in throttle and not dying too. Here's the link to my video. I hope this helps some one else that may have the same problems with their Johnson. Parts probably came out to about $50 and 4 hours of work.
http://youtu.be/OxHD_EW6FIc
Thanks for all of the suggestions.
1975, Johnson 25HP, Tiller Short staff Engine shuts off while going full speed ah
Here's the answer. Opened up the lower unit. Replaced the water pump wheel. The original had bent spokes. Probably not spinning correctly and shooting the water up to the engine and overheated the engine, which caused it to die. Because it over heated, Totally blew the rubber head gasket. Lost total compression in the pistons.
Also sanded down the gasket cover fitting to make sure it was smooth again. Luckily, the carbs and cylinders weren't destroyed or baked. Put that back together. Pulled the plugs. Checked the compression. Close to 110. Not great but not too bad. Changed the spark plugs. Removed the temperature cover and the thermostat was fried. Took thermostat out all together and left it out (some people say you need it, some say you don't). Ran the motor and water was spewing up out so the lower unit water pump wheel was most likely the culprit. I put thermostat cover back on. I also changed the condensers, and the wires to the 2 blue spark boxes. Forgot the name of those. Put in a new rubber gasket in the fuel adjuster lever too (tiny rubber band looking thing). Ran some carb cleaner in the carb while running (in water tank). Smoked like hell. Checked lower unit lube and that is fine. Running Yamalube Gear Grease in the Lower unit. Running 50:1 Yamalube M-2 in the gas tank. The motor is running fine, spitting water out fine. Got it onto the lake and it runs like a beast. No problems as of yet. Runs smooth and because I adjusted and fixed the small rubber gasket in the fuel adjuster, idle is nice and slow when not in throttle and not dying too. Here's the link to my video. I hope this helps some one else that may have the same problems with their Johnson. Parts probably came out to about $50 and 4 hours of work.
http://youtu.be/OxHD_EW6FIc
Thanks for all of the suggestions.
